RE: Rich mixture does not produce blue smoke on the exhaust!
Any setting on any needle provided by anyone is a GUIDELINE. There is NO WAY you will use the same setting all the time. Air temp, humidity, barometric pressure, altitude, condition of glow plug, engine temp, etc will cause some tuning issue, meaning you will always need to tweak the hi-speed.
When running a nitro car, you should be carrying a screw driver for those needle adjustments. Heck, on some cars, the amount of fuel in the tank affects the tune.
An engine that is TOO TOO RICH will run...but not scream like it is really loose and ready to zoom. Doubt that it can make smoke, because a nitro engine can make smoke when it really lites up, like coming out of a turn, or opening up on a stretch. "Bogging" is tough to describe...so stick with this: Too rich means it can open up...but it will never stall. Can't open it up and feel it screaming, then no chance to make smoke (esp since the engine ain't hot).
Lean it out 1/12 of a turn and try and repeat if necessary.